SURGERY: General surgery pharmacology

Cefuroxime

Drug class: Second-generation cephalosporin antibiotic. | Uses: Susceptible bacterial infections; surgical prophylaxis for selected procedures. | Side effects: Diarrhoea, nausea, rash, allergic reactions and antibiotic-associated colitis. | Contraindications: Severe hypersensitivity to cefuroxime or relevant beta-lactams. | Important cautions: Check allergy history, renal function, cultures and local antimicrobial policy.

Metronidazole

Drug class: Nitroimidazole antimicrobial. | Uses: Anaerobic bacterial infections, selected intra-abdominal infections and surgical prophylaxis. | Side effects: Nausea, diarrhoea, metallic taste and peripheral neuropathy with prolonged use. | Contraindications: Hypersensitivity; check product-specific restrictions. | Important cautions: Review interactions, particularly with warfarin, and follow current UK alcohol, pregnancy and breastfeeding advice.

Co-amoxiclav

Drug class: Aminopenicillin plus beta-lactamase inhibitor. | Uses: Selected respiratory, skin, dental and intra-abdominal infections. | Side effects: Diarrhoea, nausea, rash, candidiasis and hepatic injury. | Contraindications: Previous co-amoxiclav-associated jaundice or hepatic dysfunction; serious beta-lactam hypersensitivity. | Important cautions: Check allergies, renal and liver function, and local antimicrobial guidance.

Meropenem

Drug class: Carbapenem beta-lactam antibiotic. | Uses: Selected severe or complicated bacterial infections. | Side effects: Diarrhoea, nausea, rash, liver enzyme changes and rarely seizures. | Contraindications: Serious hypersensitivity to meropenem or relevant beta-lactams. | Important cautions: Reserve for appropriate indications, check renal function and cultures, and note the important interaction with valproate.

Senna

Drug class: Stimulant laxative. | Uses: Short-term constipation treatment. | Side effects: Abdominal cramps, diarrhoea, dehydration and electrolyte disturbances. | Contraindications: Intestinal obstruction, ileus and acute unexplained abdominal pain. | Important cautions: Avoid prolonged unsupervised use; hypokalaemia may increase digoxin-related risks.

Lactulose

Drug class: Osmotic laxative. | Uses: Constipation; hepatic encephalopathy under a separate regimen. | Side effects: Flatulence, bloating, cramps and diarrhoea. | Contraindications: Galactosaemia and bowel obstruction. | Important cautions: Excessive diarrhoea can cause dehydration and electrolyte disturbances.

Docusate

Drug class: Stool-softening laxative. | Uses: Selected cases of constipation. | Side effects: Abdominal cramps, nausea and diarrhoea. | Contraindications: Intestinal obstruction and acute unexplained abdominal pain. | Important cautions: Reassess persistent constipation and investigate possible underlying causes.

Bisacodyl

Drug class: Stimulant laxative. | Uses: Short-term constipation treatment and selected bowel preparation regimens. | Side effects: Abdominal cramps, diarrhoea, dehydration and electrolyte loss. | Contraindications: Intestinal obstruction, ileus, severe dehydration and acute unexplained abdominal pain. | Important cautions: Avoid prolonged unsupervised use.

Glycerol suppositories

Drug class: Rectal laxative with osmotic and local stimulant effects. | Uses: Short-term relief of constipation. | Side effects: Rectal irritation, abdominal discomfort and diarrhoea. | Contraindications: Suspected obstruction; check product-specific restrictions. | Important cautions: Use gently and consider suitability after anorectal surgery or with rectal pathology.

Phosphate enema

Drug class: Rectal saline/osmotic laxative. | Uses: Short-term bowel evacuation for constipation or selected procedures. | Side effects: Rectal irritation, dehydration and potentially serious electrolyte disturbances. | Contraindications: Bowel obstruction or perforation; additional restrictions apply in some renal conditions. | Important cautions: Particular risk in older, frail, dehydrated or renally impaired patients; avoid repeated doses unless directed.

Ispaghula husk (Fybogel)

Drug class: Bulk-forming fibre laxative. | Uses: Constipation and regulation of stool consistency. | Side effects: Bloating, flatulence and abdominal discomfort; obstruction can occur if taken without adequate fluid. | Contraindications: Intestinal obstruction, faecal impaction or inability to swallow sufficient fluid. | Important cautions: Take with the recommended amount of water; avoid if obstruction is suspected.

Omeprazole

Drug class: Proton pump inhibitor (PPI). | Uses: Gastro-oesophageal reflux disease, peptic ulcer disease and selected gastroprotection. | Side effects: Headache, abdominal pain, nausea, diarrhoea or constipation; prolonged use may contribute to hypomagnesaemia and vitamin B12 deficiency. | Contraindications: Hypersensitivity; check product-specific restrictions. | Important cautions: Can reduce clopidogrel activation; review indication, duration and interactions.

Lansoprazole

Drug class: Proton pump inhibitor (PPI). | Uses: Reflux disease, peptic ulcer disease and selected gastroprotection. | Side effects: Headache, abdominal pain, nausea, diarrhoea or constipation. | Contraindications: Hypersensitivity; check product-specific restrictions. | Important cautions: Review duration, interactions and hepatic impairment.

Ondansetron

Drug class: Serotonin 5-HT3 receptor antagonist antiemetic. | Uses: Prevention and treatment of nausea and vomiting, including postoperative nausea and vomiting. | Side effects: Headache, constipation and QT prolongation; rarely serotonin syndrome. | Contraindications: Concomitant apomorphine is a key contraindication. | Important cautions: Assess QT risk, electrolytes, cardiac history and interacting medicines.

Cyclizine

Drug class: H1 antihistamine with antimuscarinic effects. | Uses: Nausea and vomiting, including selected postoperative or vestibular causes. | Side effects: Drowsiness, dry mouth, blurred vision, constipation and urinary retention. | Contraindications: Check product-specific restrictions. | Important cautions: Use caution in glaucoma, prostatic enlargement, urinary retention and older adults at risk of confusion or falls.

Metoclopramide

Drug class: Dopamine D2 receptor antagonist with prokinetic effects. | Uses: Short-term treatment of nausea and vomiting in selected indications. | Side effects: Drowsiness, diarrhoea, acute dystonia and other extrapyramidal reactions. | Contraindications: Gastrointestinal obstruction, haemorrhage or perforation; Parkinson disease; epilepsy; concomitant levodopa or dopamine agonists. | Important cautions: UK use is generally restricted to a maximum of 5 days; adjust for renal impairment where indicated.

Gastrografin

Drug class: Water-soluble iodinated gastrointestinal contrast medium. | Uses: Selected gastrointestinal imaging and assessment of suspected leaks or obstruction. | Side effects: Nausea, vomiting, diarrhoea and hypersensitivity; aspiration can cause severe lung injury. | Contraindications: Depend on route and clinical context; check product information. | Important cautions: Hyperosmolar preparations can cause fluid and electrolyte shifts; assess aspiration risk.

Barium contrast

Drug class: Positive-contrast gastrointestinal imaging agent. | Uses: Selected gastrointestinal radiographic or fluoroscopic studies. | Side effects: Constipation, faecal impaction and rare reactions to formulation ingredients. | Contraindications: Suspected gastrointestinal perforation when leakage of barium would be hazardous. | Important cautions: A water-soluble contrast agent may be preferred if a leak or perforation is suspected.